This invention relates to the field of stabilizers used in the oil well drilling operations to aid in drilling directional holes, straight holes and to prevent "sticking" between the drill string and the bore hole by having the blades of the stabilizer prevent the drilling string from contacting the sides of the well bore hole. In the past, stabilizers were made up within the drill string as the string was run into the hole; however, this arrangement has several undesirable features because it adds tool joint connections to the drill string, which increases possible points of failure in the drill string and causes variation in drill collar stand lengths which increases trip time and creates unsafe operational conditions for rig personnel and further requires a special bottom hole assembly which increases drilling costs and does not permit adjustment of the stabilizer along the drill string without changing subs which further increase drilling costs.
The use of lock-on stabilizers has been suggested to solve these undesirable aspects. Typically, the lock-on stabilizer has a body with externally extending blades, two end caps for connecting to the body, an inside solid locking ring and two outside solid locking rings with a single tapered surface for each ring. The stabilizer is connected between pin and box joints on the drill string by positioning the inside locking ring inside the body, thereafter positioning an outside locking ring on either end of and with the tapered surface facing the inside locking ring. Two end caps are used to force the rings together within the body to connect the stabilizer to the drill string. A major difficulty with this arrangement has been its inability to be reused after once being attached. This difficulty is caused by the inherent inability of the solid rings to clamp around the drill string without being deformed.
As further set forth in U.S. Pat. No. 3,916,998, U.S. Pat. No. 4,101,179 and U.S. Pat. No. 4,105,262, combinations of split rings and/or wedging clamps are used for attaching the stabilizers to the drill string.
It is one object of the present invention to provide a stabilizer of simple and inexpensive construction which is releasably connected to a drill string.